Also offers two ways to output Kripke structures.

* src/kripketest/parse_print_test.cc, src/kripke/kripkeexplicit.cc
: Simplify includes.
* src/kripke/kripkeprint.hh (kripke_save_reachable,
kripke_save_reachable_renumbered): New declarations.
(KripkePrinter): Move and rename...
* src/kripke/kripkeprint.cc (kripke_printer): ... here.
(kripke_printer_renumbered): New class.
(kripke_save_reachable, kripke_save_reachable_renumbered): New
function.
* src/tgbatest/ltl2tgba.cc: Add an option to read Kripke
structures.
* iface/dve2/dve2check.cc: Use kripke_save_reachable_renumbered.
* iface/dve2/defs.in (run2): Remove.
* iface/dve2/kripke.test: Adjust tests.